This invention relates to a planar waveguide structure for transmitters and receivers wherein active semiconductor component elements, which are connected with planar conductors, are arranged on the front side of a semiconductor substrate.
The invention finds application in the manufacture of monolithic integrated millimeter wave transmitters and receivers having beam-forming elements, for example, for radar transmitters and receivers in motor-driven vehicles.
A planar waveguide structure consists of a structured metallization or coating of a substrate, which may be a layered substrate, in one or more planes. By virtue of a special geometric configuration of the metal coating, different structures, for example, couplers, resonators and antennae, may be formed.
Planar waveguides are capable of guiding microwaves. Such waveguides may be coupled with active semiconductor component elements to form monolithic integrated circuits. The semiconductor substrate must be high ohmic or must be a semi-insulator. Silicon is suitable as a high ohmic material, while GaAs is suitable as a material for a semi-insulating substrate.
A planar waveguide structure radiates upwardly, for example, into air, and downwardly, into the substrate. The irradiation into the substrate is in general greater than the outward radiation.
Transmitters and receivers for electromagnetic waves in the millimeter wavelength range having planar waveguide structures are described, for example, in the periodical "Mikrowellen und HF Magazin", Volume 14, N. 8, pages 750-760. The transmitters and receivers in the millimeter wavelength range described therein are manufactured with the silicon monolithic microwave integrated circuit technique. Antennae or lenses are used for shaping, in a predetermined manner, the radiation transmitted by transmitters or received by receivers of this type.